Function appendParam

Utilities for uri

Author

David Hsing

appendParam(
source?: null | string,
param?: null | string,
): undefined | null | string
Returns the joined string that represent the given source and param
Parameters
- Optionalsource: null | string
  The source uri to prepend
- Optionalparam: null | string
  The target param to append
Returns undefined | null | string
the joined string that represent the given source and param
Author
David Hsing
Example
```
appendParam(undefined, 'foo=bar');    // 'foo=bar'
appendParam('unikue.cn/donation', undefined);    // 'unikue.cn/donation'
appendParam('unikue.cn/donation', 'foo=bar');    // 'unikue.cn/donation?foo=bar'
appendParam('unikue.cn/donation?from=today', 'foo=bar');    // 'unikue.cn/donation?from=today&foo=bar'
```